Weak Localization and Electron-Electron Interaction in Si/SiGe Quantum Wells

A negative magnetoresistance is observed in Si/SiGe modulation doped heterostructures which is attributed to the single particle quantum interference (weak localization) effect. From analysis of the experimental data the electron phase coherence time τ$\text{}_{ϕ}$ is extracted to follow a (aT + bT$\text{}^{2}$ )$\text{}^{-1}$ dependence. The evaluated prefactor α = 0.25 is below the theoretical limit of 0.5, but agrees with observations in Si and GaAs/AlGaAs heterostructures.